So they promised a checker and that turned out to be a version of testdisk that supports BtrFS. Awesome! Not.
Not releasing the code for checker a long time ago was a mistake and waiting only makes it worse. So why isn't there code? Sure people will frag their FS, so what. Tell people it eats babies in flashing red letters for a minute before they use it. BtrFS is not production ready. If some of those users provides a good bug report we will get a working BtrFS a lot sooner.